首页|Triggering synergistic deformation mechanisms by migration of Cu-rich nanoprecipitates in medium-Mn steel

Triggering synergistic deformation mechanisms by migration of Cu-rich nanoprecipitates in medium-Mn steel

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  • NETL
  • NSTL
  • Elsevier
Medium Mn steel (MMS) is attractive for lightweight design and a variety of structural applications due to its high strength and high plasticity, but it often face the "strength-plasticity trade-off'. The cooperative strengthening of transformation-induced plasticity (TRIP) effect and precipitation strengthening has the potential to overcome this problem in Medium Mn steel, however, it is usually not easy to introduce high-density nano-precipitation in soft and metastable austenite. Here, we report a nanoprecipitation migration strategy for the design of Cu bearing MMS by combing pre-precipitation, dynamic reversed transformation and re-precipitation, which achieves precipitation of high density of Cu-rich nanoparticles in the austenite and simultaneous enhancement of strength and plasticity. In warm-rolling and tempering MMS (1.63 wt% Cu addition), a large number of Cu-rich nanoprecipitates formed near the interface between austenite and ferrite during the annealing before warm-rolling. Cu-rich nanoprecipitates dissolved into clusters and heterogeneous Mn distribution occurred in the austenite during warm-rolling, moreover, phase interface migration caused the Cu-rich nano-clusters to remain in the austenite due to dynamic reversed transformation. Re-precipitation of high density of Cu-rich nanoparticles in the austenite based on these nanoclusters and heterogeneous Mn distribution during the tempering after warm-rolling. In contrast to the unrolling steels, the number density of Cu-rich nanoprecipitates in austenite increases from 4.43 × 10~(21) m~(-3) to 2.68 × 10~(22) m~(-3) in warm-rolling and tempering steels. These Cu-rich nanoprecipitates remarkably strengthened the austenite, improved the austenite stability and reduced the strain incompatibility between austenite and ferrite, which contributed to progressive transformation of austenite and spectral TRIP effect. Consequently, an increase in uniform elongation of 9 % along with an improvement in yield strength of 120 MPa and without drop of tensile strength was achieved in Cu bearing MMS. This work demonstrates how synergistic strengthening mechanisms can be activated by tailoring the number density of nanoprecipitates in metastable phase, along with the chemical/mechanical driving force for metastable phase transformation, to optimize strength and plasticity.

Strain incompatibilityCu-rich nanoprecipitatesNanoprecipitation migrationTRIP effectAustenite stabilityPrecipitation hardening and plasticizing steels

Kaihao Guo、Zelin Tong、Yuantao Xu、Yunting Li、Wei Li、Hongshan Zhao、Hao Du、Chenghui Xia、Xin You、Wenqing Liu、Xuejun Jin

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Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai, 200240, PR China||School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China

School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China||Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai Jiao Tong University, Shanghai, 200240, PR China

School of Materials Science and Engineering, Shanghai University, Shanghai, 200444, PR China

Key Laboratory for Microstructures, Shanghai University, Shanghai, 200444, PR China

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2025

10.1016/j.msea.2024.147712

Materials science and engineering, A. Structural materials

Materials science and engineering, A. Structural materials

ISSN：0921-5093
年,卷(期)：2025.924(Feb.)
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